Even if you don’t really care about online safety, which, to be honest, is kind of strange, because these days it’s worth thinking about it even when everything seems fine, I’m sure many people would still want to separate personal life and work. I have a lot of communication with clients I talk to only once. I definitely don’t want to give them my personal phone number, and virtual numbers from smsfast.com are very convenient for this. My real phone number is used only for personal life, personal chats, friends and family. Maybe your friends use such numbers for the same reasons.